The present invention relates to a packaging and cooking system for microwave cooking of one or more food items. In particular, the invention is directed to a packaging system for microwave cooking of food items that provides relatively crisp outer surfaces, while adequately heating and cooking the interior portion of the food items.
Microwave ovens provide to consumers a quick and convenient option for cooking and heating food products that typically requires less time and effort than that involved when heating the same food products in a conventional oven. However, heating foods in a microwave oven involves different considerations than heating foods in a conventional oven. In particular, conventional ovens operate by maintaining a relatively constant and homogeneous high temperature environment in which food products are placed for cooking and/or warming. The conventional oven heat initially warms the outer surfaces of the food product, and then this heat gradually progresses toward the center of the food by conduction or other heat transfer mechanisms. Because the outer surfaces of the food product are warmed first, moisture is driven away from the outer surface of the food product, thereby providing an outer surface that is more likely to be crisp than to be soggy or soft.
In contrast, microwave cooking or heating involves the use of electromagnetic radiation at a high intensity and high frequency. The radiation is transmitted to the food product so that the radiation or microwaves penetrate a substantial distance into the interior portion of the food product. Heating of the food product, and particularly the interior portion of the food product, occurs as the food absorbs this electromagnetic energy. Thus, the interior portion of the food product is typically heated much more quickly than the exterior surface, which causes the moisture to be driven from the center of the food product to the surface. In addition, microwave energy often causes the interior portion of the food to reach its desired serving temperature while the exterior surface is only partially warmed. This temperature of the exterior surface is typically not high enough or is not maintained at a high temperature for a long enough time to drive sufficient moisture away from the surface. This will typically result in a product that is soggy on the outside, but cooked and warmed on the inside. While it is possible to continue to subject the food product to additional microwave energy in an effort to drive excess moisture away from its outer surface, such additional heating of the product can increase the interior temperature of the food product so much that it detrimentally affects the quality of the food product (i.e., the interior portion is overcooked) and/or makes the product too hot for the consumer to eat.
Methods and devices have been developed to attempt to reduce the moisture content of the outer surfaces of microwaved food products to a sufficiently low level that the product surfaces are perceived as crisp to the consumer. xe2x80x9cCrispnessxe2x80x9d, as the term is used herein, refers primarily to the taste and touch sensation characteristics experienced by the consumer who is holding and eating a particular food product. In particular, a product surface that is crisp may be described as relatively brittle and dry to the touch, as opposed to soggy product surfaces that are relatively soft and moist to the touch. Many previously developed methods and devices include the use of a susceptor material that is in close proximity to or in direct contact with a food product surface for the purpose of heating that surface to a higher temperature so that it can become more crisp. These susceptors typically include a sheet or film having a conductive coating, such as a metallized film, which absorbs microwave energy during exposure to microwave fields. As described in U.S. Pat. No. 5,041,295 (Perry et al.), commonly owned by the assignee of the present invention, the perception of crispness may be achieved by providing a food product that is generally crisp on only one surface, as long as the other surfaces of the food product are not particularly soggy or mushy. Perry et al. achieves this crispness on one food product surface through the use of a susceptor located in close proximity to or in direct contact with one surface of the food product.
Other examples of attempts to achieve crisping involve using flexible wrapping material including a microwave susceptor layer or material. The wrapping material is wrapped completely around a food product to contact all or most of the outer surface area of the product. Unfortunately, these methods often prevent or inhibit the movement of sufficient moisture from the exterior surfaces of the food product, which can thereby cause the product to be soggy. In addition, when a package is provided with multiple food products that are relatively small (e.g., fish sticks or pizza rolls), it can be cumbersome and time-consuming to place each food product into its own flexible wrapping material, and then remove each product from its wrapping material after cooking in the microwave.
A further issue with these systems using flexible wrapping material is that the material is typically provided in a kit that includes multiple components with which the user must perform multiple operations to cook the food product or products. For example, a filled pizza dough product can be provided in an outer shipping package that includes the filled dough product within a plastic wrapper and a separate cooking sleeve made of a flexible wrapping material. To cook the product, the consumer would first open the outer shipping package to access the food product and the cooking sleeve. The consumer would then remove the food product from the shipping package and its plastic wrapper and slip the cooking sleeve over the food product. The consumer would then place the food product and sleeve in the microwave on a separate plate or napkin to keep the food product from directly contacting the microwave oven surfaces. After the food product is cooked, the consumer must remove the sleeve from the product and would then typically place the product on some other serving piece for consumption of the product. This process creates several disposable packaging and cooking items, and requires the consumer to follow several steps for proper cooking of the food product. Further, as explained above, these cooking sleeves often do not produce the desired levels of crispness since excess moisture is trapped between the sleeve and the outer surface of the food product, which typically causes the outer surface of the food product to become soggy.
Another factor that can make consistent crisping of microwaved food products difficult is the variability in the size of individual food products. Although food product manufacturers typically have specifications for the volume of various food components that go into each individual product, the tolerances on the exact size and shape of the finished products can be relatively loose to accommodate for environmental variability, raw material differences, and other factors. For example, changes in the operating conditions of the production machinery and even slight differences in the physical properties of the food materials can result in products that are slightly different from each other in size and shape. In some cases, the different sizes and shapes of various products that are cooked in a microwave at the same time can result in different heating and crisping of the products. That is, some of the food products could be at a desired temperature and crispness, while other products are either too hot or cold, and may also be more or less crisp than desired.
It is therefore desirable to provide a packaging and cooking system that is easy and convenient for the consumer and that can provide food products that have consistently crisp outer surfaces and interior surfaces that are heated to a uniform desired serving and consuming temperature. It is further desirable to provide such a system that minimizes packaging waste and minimizes the number of steps that need to be executed to produce a product having the desired temperature and crispness.
In one aspect of this invention, a reconfigurable microwave packaging container is provided for containing, heating, and crisping at least one surface of at least one food product. The container includes a reconfigurable first panel having a flap that is at least partially separable from the container, and at least a portion of the flap includes a microwave susceptor material for absorbing microwave energy to transfer to at least one food product surface. The container also includes a second panel spaced from the first panel by a first distance to accommodate at least one food product between the first and second panels. The flap of the first panel is reconfigurable to be spaced at a second distance from the second panel, wherein the second distance is smaller than the first distance.
The flap of the container may include at least one fold line to facilitate the reconfiguration of the flap. At least one part of the flap may also be reconfigurable to contact an outside surface of at least one food product. The container may also include at least one gap between the flap and one of the container panels to allow steam to escape from the container during the microwave cooking process. The container may include at least one food product that is microwavable to achieve an outer food product surface that is crisper than an interior portion of the food product, where this food product may be a filled dough product, such a pizza roll.
The present invention also includes a method of containing, heating, and crisping at least one food product. This method includes the steps of providing a reconfigurable container having a first panel, a second panel spaced from the first panel, and at least one food product positioned between the first and second panels. The first panel includes a microwave susceptor material and a flap having a fold line. The method further includes partially separating the flap from the container, folding the flap along the fold line, and pressing the flap toward the second panel of the container until the microwave susceptor material of the flap contacts the at least one food product within the container. Microwave energy is then applied to the container so that the food products are heated by a predetermined amount.